According to [1]}, a discrete-time dynamic
feedback is said to be endogenous, if its states \(z\)  and inputs \(v\) 
can be expressed as functions of \(x\) , \(u\)  and forward-shifts of
\(u\) . It can be shown that the class of discrete-time systems that
is linearizable via endogenous dynamic feedback in the sense of [1]}
exactly corresponds to the class of forward-flat systems. In this
section, we show that also for flat systems according to Definition
REF  there always exists a linearizing discrete-time
dynamic feedback
\(\begin{aligned}z^{+} & =\alpha (x,z,v)\\u & =\beta (x,z,v)\,.\end{aligned}\) 
